Two years ago at Google Inc.'s annual developer conference, skydivers wearing Google Glass parachuted from an airplane to unveil the Internet-connected eyewear. This year, Glass wasn't mentioned during the conference keynote.

Instead, Google touted new software to power wearable devices like smartwatches that do many of the same things as Glass. The smartwatches are much cheaper, offer far more apps, and don't come with the social...